Young plants and trees are commonly raised in containers from seeds planted in nursery soil and subsequently transplanted to a desired location. By the use of such containers transplanting shock can be eliminated and retention of nutrients and moisture within the confines of containers can be maintained for a period after field planting.
Such containers, which can be formed of plastic resin materials, also facilitate mechanized planting of the plants or trees as, for example, taught in Canadian Patent 694,803, and U.S. Pat. Nos. 3,517,629 and 3,736,889. In this approach a gun-like device implants the plastic container containing the seedling plant or tree in the ground. The problem encountered by this method is designing the plastic container or projectile so that it is strong enough to be driven into the ground and yet readily breakable once in the ground so that the seedling roots can be properly established in the soil.
The mere provision of slits or holes in the container, while permitting some root egress, will ultimately result in root strangulation unless it breaks apart or disintegrates. The incorporation of degradable materials in the plastic material of the container has yet not proven fully satisfactory. If the material is water degradable, the container will at least partially dissolve during irrigation in the nursery with the result that it has insufficient strength for transplanting. Where certain biodegradable compositions have worked reasonably well they have been generally too expensive for use in this application. If the plastic contains reasonably priced biodegradable concentrates, it tends to be degradable too fast in the nursery due to exposure to ultraviolet light, and too slow after planting.
Where other less expensive techniques have been used, such as using prestressed glass, it has been necessary for someone to come along after planting to fracture the container so that it would break into many pieces.
It is therefore among the objects of this invention to provide an improved economical planting container which will have adequate strength to be implanted by a gun-like device after sustaining the seedling in the nursery and, after implantation, self-destruct.